Heat triggered door jamming mechanism

Abstract

A push door opening mechanism for use where protection from fire is sought. In operation the push handle causes a spring biased operating lever to rotate within the door opener. The operating lever pulls a bolt which allows the door to open. When the lever is in the return position, a cavity in the operating lever is positioned adjacent to a locking pin. That pin is held in the base plate and is longer than the depth of the cavity in the operating lever. The locking pin is also mechanically biased to move into the cavity. Once positioned in the cavity, the rotation of the operating lever is jammed because the locking pin is partially in the operating lever and partially held rigid in the base plate. However, during normal operation, the locking pin is retained out of the cavity by a low melting point fusible link pin. During a fire the base plate becomes hot, causing the link pin to melt which frees the locking pin. The locking pin then moves into the cavity in the operating lever and jams the push door opener.

I claim: 
     
       1. A push-actuated door opener, for use on a door, comprising: a base plate for attachment to a door;   an elongated axially moveable bolt which, when pulled into the door, allows it to open;   a push lever having a projection and a handle and means pivotally connecting the push lever to the base plate;   an operating lever having a cavity of a predetermined depth and means pivotally connecting the operating lever to the base plate, the operating lever further having a return position and being connected to the projection of the push lever on the base plate such that the operating lever rotates out of the return position to pull the bolt into the door when the push handle is pressed;   means for urging the operating lever to the return position;   a locking pin which is longer than the depth of said cavity in the operating lever, the locking pin being held in the base plate opposite the cavity and means biasing the locking pin toward the cavity; and   a fusible link pin, connected to the base plate and positioned to retain the locking pin in the base plate out of the cavity when said fusible link pin has not been exposed to a high temperature but permitting said locking pin biasing means to move said locking pin when exposed to a high temperature.   
     
     
       2. A push-operated door opener as in claim 1, in which at least the base thereof is made of a highly efficient heat conductor. 
     
     
       3. A push-operated door opener as in claim 1, where the operating lever further comprises: a first and a second arm which are substantially mutually orthogonal, the first arm contacting the projection of the push lever such that the actuation of the push handle causes the push lever to rotate about a first pivot pin, causing the projection to move the first arm, whereby the operating lever rotates about a second pivot pin and further the second arm of the operating lever pulls the bolt into the door.   
     
     
       4. A push-operated door opener as in claim 3, wherein the first pivot pin is perpendicular to the second pivot pin. 
     
     
       5. A push-operated door opener as in claim 4, wherein the first pivot pin is horizontal and the second pivot pin is vertical. 
     
     
       6. A push-operated door opener as in claim 1, wherein the means for urging the operating lever is a torsional spring which contacts both the operating lever and the base plate. 
     
     
       7. A push-operated door opener as in claim 1, wherein the means for biasing the locking pin is a compressed spring. 
     
     
       8. A push-operated door opener as in claim 1, wherein the locking pin is above the operating lever. 
     
     
       9. A push-actuated door opener, for use on a door, comprising: a base plate for attachment to a door;   an elongated, axially moveable bolt which, when pulled into the door, allows it to open;   a push lever having a projection and a handle, the push lever being connected to the base plate on a first pivot pin;   an operating lever having a cavity of a predetermined depth, the operating lever being held on the base plate on a second pivot pin which is perpendicular to the first pivot pin, the operating lever further having a return position and being connected to the projection of the push lever on the base plate such that the operating lever rotates out of the return position to pull the bolt into the door when the push handle is pressed;   a torsional return spring which contacts both the operating lever and the base plate, and which urges the operating lever to the return position;   a locking pin which is longer than the depth of the cavity in the operating lever, the locking pin being held in the base plate opposite cavity in the operating lever, but not below the cavity and further the locking pin urged toward the   cavity by a bias spring; and   a fusible link pin, connected to the base plate and positioned to retain the locking pin in the base plate out of the cavity.